In general, exhaust gases of a vehicle contain a large amount of harmful substances, such as carbon monoxide, nitrogen oxides, and hydrocarbon. In particular, an amount of harmful substances, such as nitrogen oxides, etc., increases as temperature of an engine becomes higher. In order to reduce the amount of the harmful substances, an exhaust gas recirculation (EGR) system may be used since it decreases combustion temperature in a cylinder by recirculating the exhaust gases to an intake system. Further, an EGR cooler for cooling the exhaust gases of high temperature with a coolant fluid may be installed in the EGR system.
Further, a large amount of heat in the engine of the vehicle is generally discharged as waste heat, and a waste heat recovery system by converting waste heat to usable energy has been developed for increasing efficiency of the engine. The waste heat recovery system is configured to collect waste heat discharged from the engine and convert the collected waste heat to electrical energy or mechanical energy which may be used for the engine or other accessories of the vehicle.
Particular for a commercial vehicle, EGR gas of the EGR system may be utilized as an important heat source of a waste heat recovery system, an EGR gas boiler for heating a working fluid with waste heat of the EGR gas may be installed in a Rankine cycle of the waste heat recovery system.
An EGR gas boiler may be a cooler for cooling the EGR gas. When a volume and/or an installation location of the EGR gas boiler are designed, an EGR cooler needs to be considered. For example, because it is difficult to obtain a target cooling temperature (e.g., less than approximately 140° C.) only with an EGR gas boiler, it is necessary to have an EGR cooler such that the EGR cooler is adjacent to the EGR gas boiler.
In addition, it is necessary to maintain the EGR cooler in order to cope with a situation, such as an initial driving stage of the vehicle, a breakdown of the waste heat recovery system, or the like.